1. The Field of the Invention
The present invention relates to inflatable safety cushions, or airbags, for vehicles. More specifically, the present invention relates to a novel airbag especially suited to protecting vehicle occupants from side impacts or rollovers, and a low-cost and convenient method for manufacturing, assembling, and installing such an airbag.
2. The Relevant Technology
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the ignition of an explosive charge. Expanding gases from the charge fill the airbags, which immediately inflate in front of the driver and passenger to protect them from impact against the windshield.
Side airbags have also been developed in response to the need for similar protection from impacts in a lateral direction, or against the side of the vehicle. However, side airbags known in the art have a number of disadvantages. First of all, many known side airbags have insufficient gas retention capability to protect a vehicle occupant beyond a brief initial impact. The seams created during fabrication of the airbag, and sometimes the fabric of the airbag itself, are often too permeable to retain gas for any length of time. Many taller vehicles, such as sport utility vehicles, are prone to rollover during tighter turns. The rollover is not just a single impact, but a series of jarring motions, all of which are potentially dangerous to vehicle occupants. Many previously known airbags will deflate before the vehicle comes to a stop, a process that could take several seconds.
Furthermore, many airbags are too bulky for convenient installation and use in a vehicle. The airbag must be mounted some distance from a passenger because the airbag requires space to inflate. The speed at which the airbags in general, and especially side airbags, must deploy to adequately protect people requires that they inflate with considerable speed and force. Placement too close to a vehicle occupant increases the risk that the occupant will be injured by the airbag itself.
Some more compact vehicles simply do not have the space to accommodate the bulk of currently available, side impact airbags. Seatbelts are somewhat effective in restraining forward motion of an occupant, as in a head-on collision, but they leave a person more or less unprotected from sideways motion. As a result, people in compact vehicles are now unable to obtain any significant protection from lateral impact and rollovers.
Unfortunately, even in vehicles large enough to hold side impact airbags, it is difficult to properly mount and hide the airbags in the vehicle. Airbags mounted in a visible, accessible location are to be avoided because they are unsightly and may be tampered with by children and others. Unfortunately, the bulk of current airbags makes it difficult to mount the airbags within the frame or interior paneling of the vehicle. Although suitable cavities may be formed in a steering wheel or dash board to receive an airbag module, it is far more difficult to create a similar amount of free space on the side of the vehicle without completely redesigning large portions of the vehicle. This increases the expense and inconvenience involved with the use of side impact airbags.
Additionally, many side impact airbags are incapable of protecting more than a single occupant without the use of additional gas sources or complex ducts to convey gas to multiple cushions. Use of multiple gas sources adds to the complexity of a vehicle because a suitable space must be formed for each gas source, and all gas sources must either have their own accelerometers, or they must have wiring routed to them from a common accelerometer. Routing ductwork through the doors or other portions of a vehicle is similarly inconvenient, because the ducts often intersect other essential components inside the vehicle frame. This adds to the expense and bulk of side airbag systems and often requires a vehicle manufacturer to make specific modifications in the design of the vehicle to accommodate the airbag. Furthermore, longer ducts restrict the flow of inflation gases, thereby creating a lag in the airbag""s deployment. The speed at which side impact bags must open to provide effective protection makes any significant lag unacceptable.
Yet further, previously-known side impact airbags are expensive to produce and install. Most airbags are constructed either of a single piece of material, or two separate pieces of like material sewn together. Consequently, standard airbag material is used throughout, despite the fact that the user contacts only a portion of the airbag when it deploys. This tends to increase the cost and bulk of the airbag. For larger vehicles, in which the airbag must cover an impact surface of considerable size, side impact airbags may require a very large amount of material.
Accordingly, a need exists for a safety restraint apparatus capable of retaining gas for several seconds, as during a rollover. Furthermore, there is a need for a side airbag device that requires little space on the inside of the vehicle. Moreover, a need exists for a side airbag able to protect multiple occupants of a vehicle from side impact and rollovers without the use of several gas sources. A need further exists for an airbag that is simple in design and construction, so as to be producible at low cost.
The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available safety restraint systems. In accordance with the invention as embodied and broadly described herein in the preferred embodiment, a novel side impact airbag for a vehicle is provided.
In one embodiment, the side impact airbag comprises a cushion portion connected to a source of pressurized gas via a supply tube fabricated separately from the cushion portion. The supply tube is preferably constructed of a pliable material, such as a plastic or fabric, and is preferably attached to the cushion portion by sewing, RF welding, adhesive bonding, or chemical bonding. The airbag may be arrayed along the inside of the vehicle roof, where the front door meets the frame of the vehicle. The supply tube may be mounted along the strut extending along the edge of the windshield. The source of pressurized gas, which may take the form of a canister of gas-producing material, may be mounted within the dashboard or engine compartment of the vehicle.
In an alternative embodiment, multiple cushion portions may be used to provide protection for additional passengers. For example, a second cushion portion may be installed to the side of the rear seat and connected with the first cushion portion by a first sail portion. The first sail portion may be separately fabricated and attached to suitable ports on each cushion portion. When the first cushion portion inflates, gas travels through the first sail portion to inflate the second cushion portion as well. The first sail portion need not be made of standard airbag material, such as a fabric, but may be constructed of thin, air-retentive plastic.
Similarly, a third cushion portion may be installed to the side of an extra seat, behind the rear seat, as may be found in a minivan or sport utility vehicle. The third cushion portion may be connected to the second cushion portion by means of a second sail portion attached in similar fashion to the first sail portion. Additional cushion portions may be added and configured as needed, through the use of additional sail portions or other devices used to convey gas from one cushion portion to another.
The cushion and sail portions are preferably produced economically through modular construction. For example, xe2x80x9clay flatxe2x80x9d construction involves the formation of components from substantially flat pieces of material. The cushion portions, for example, may be stamped or cut from a sheet of fabric, in the form of two symmetrical halves. The supply tube and/or sail portions may also be manufactured as two separate halves made from a sheet of fabric and subsequently attached. The cushion portion, the supply tube, and/or the sail portion may then be attached to each other, through methods such as chemical and adhesive bonding, sewing, and RF welding.
Modular assembly enables the use of different materials to form different parts of the airbag. The cushion portion, for example, receives the brunt of the passenger""s impact, while the sail portion serves mainly to convey air to the cushion portion. Hence, the sail portion may be made thinner and lighter than the cushion portion. Hence, the entire airbag is cheaper and more compact.
Modular assembly is also beneficial because several different airbag configurations may be made with interchangeable parts. Thus, tooling for the airbag assembly line need not necessarily be changed to produce airbags for different vehicles; available components may simply be assembled differently to create the new configuration. Moreover, modular construction permits the creation of configurations that would be impossible to fabricate from a single piece of material. Additionally, flawed components do not require scrapping the entire airbag, only the flawed component.
Modular construction also makes the airbag more compact by adding flexibility in the design for different folding patterns. Airbags are typically installed in a tightly folded configuration to keep them compact and ensure that they deploy without catching on any obstacle. Through modular construction, airbags may be designed to fold evenly and with little unused space, even in the irregular, elongated spaces in which a side impact airbag may need to be installed.
The modular construction provides the flexibility to selectively coat certain parts of the airbag assembly. Interior surfaces of the first and second cushion portions maybe coated with a polymer, to improve their gas retention characteristics. The sail portion may be coated on the inside or outside as well. Preferably, the cushion portions have sail ports coated with a urethane-based coating on the inside, designed to bond to a similar coating on the outside of the sail portion through RF welding. The seams of the cushion portions and the sail portion may likewise be RF welded. Struts may be provided inside the cushion portions to ensure that they inflate to the proper shape by forming parallel chambers in the cushion portions.
These and other objects, features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.